A Micro-Electro-Mechanical System (MEMS) microphone formed by a micro electronic mechanical system process has become one of the best candidates for replacing an Electret Condenser Microphone (ECM) with organic film, due to its characteristics of miniaturization and lightweight of the MEMS microphone.
The MEMS microphone is a miniature microphone made by etching a pressure sensing diaphragm on a semiconductor using micro-electro-mechanical system process, and is widely used in mobile phone, headset, notebook computer, video camera and car. Driven by the need of MEMS microphone's compatibility with Complementary Metal Oxide Semiconductor (CMOS) and further reducing the size of the MEMS microphone, package structure for MEMS microphone has attracted many development activities in recent years. Many companies invest a lot of money and scientific manpower to study the package structure for MEMS microphone. However, a method adopted by all these companies is that a CMOS circuit and a MEMS microphone are manufactured separately, then the CMOS circuit and MEMS microphone are attached on a substrate, and finally, the CMOS circuit is coupled to the MEMS microphone by wire-bonding technology.
A package structure for the MEMS microphone is given in a paper of “Silicon microphone development and application”, Sensors and Actuators A, 2007, 133: 283-287. Referring to FIG. 1, the package structure includes a package substrate 100, which has an opening in communication with the package substrate 100, with the opening being adapted to pass through an acoustic signal; a MEMS microphone 110 and a CMOS circuit 120 adapted to control the MEMS microphone 110 which are located respectively on the package substrate 100; a wire 140 electrically coupling the MEMS microphone 110 to the CMOS circuit 120; and a package frame 130 by which the package substrate 100, the MEMS microphone 110 and the CMOS circuit 120 are covered. The CMOS circuit 120 and the MEMS microphone 110 are manufactured separately, and then are packaged on the package substrate 100 by the wire-bonding technology. The package structure for the MEMS microphone packaged on the package substrate 100 by wire-bonding technology has a large size, and needs an additional package frame 130, which has a complex manufacturing and packaging process, a large size, and high cost.